The present invention relates to a heat treatment method for actuators used in ink jet printer heads and a method for manufacturing an ink jet printer head.
As shown in FIGS. 1 and 2, an ink jet printer head is so constructed by integrally joining a piezoelectric/electrostrictive film type chip 10, into which a plurality of actuators 20 are integrated with an ink nozzle member 11 having a plurality of nozzle holes 12. Ink supplied into pressure chamber 30 formed in actuator 20 is jetted through each corresponding nozzle hole 12.
The ink nozzle member 11 is constructed by laminating a thin planar nozzle plate 13, provided with a plurality of nozzle holes 12, and a similarly thin planar orifice plate 15, provided with a plurality of orifice holes 14. A flow path plate 16 is interposed between the two and all are joined with an adhesive or the like. Inside the ink nozzle member 11, an ink jet pass 17 for supplying ink to nozzle holes 12 and ink supply flow paths 18 for supplying ink to orifice holes 14 are formed. Incidentally, these ink nozzle members 11 are normally made of metal or plastics.
An actuator 20 comprises a ceramic substrate 21 and a piezoelectric/electrostrictive operating section 22 integrally formed on the ceramic substrate 21. The ceramic substrate 21 is integrally composed of a thin planar closure plate 23 and a thin planar connection plate 24 stacked together with a spacer plate 25 interposed therebetween to form an ink pump section 29. Incidentally, the closure plate 23, connection plate 24 and spacer plate 25 are respectively formed of ceramic green sheets by lamination and integrally fired to make an ink pump section. Here, in the connection plate 24, a first communicative opening 26 and a second communicative opening 27 are formed at the respective positions corresponding to the orifice hole 14 formed on orifice plate 15 of ink nozzle member 11.
In the spacer plate 25, a plurality of window sections 28 are formed, while spacer plate 25 and a connection plate 24 are stacked together so as to allow the first communicative opening 26 and a second communicative opening 27 provided on the connection plate 24 to be opened against each window section 28. The window section 28 is closed by a closure plate 23.
In this manner, the pressure chamber 30 is formed inside ceramic substrate 21.
And, on the outer surface of the closure plate 23 in the ceramic substrate 21, the respective piezoelectric/electrostrictive operating sections 22 are provided at the sites corresponding to individual pressure chambers 30. Here, piezoelectric/electrostrictive operating sections 22 each comprises a lower electrode 31, a piezoelectric/electrostrictive layer 32 and an upper electrode 33.
As described above, the ink jet printer head comprises an actuator made of a ceramic body and an ink nozzle member, both of which are normally joined by using an adhesive.
When an actuator and an ink nozzle member are joined by using an adhesive like this to manufacture an ink jet printer head, however, there has frequently occurred a situation that the actuator and the ink nozzle member are stripped off from each other at the time of use. As a result of investigation into this situation, the present inventor found that this originated in slight traces of adhesive remaining in the actuator.
Namely, after prepared as a piezoelectric/electrostrictive film type chip 10 in which a plurality of actuators 20 are integrated as shown in FIG. 2, an actuator is adhered to a holding adhesive film such as dicing film and subjected to a given inspection if necessary to clarify whether or not the actuator 20 manifests a desired performance or the like. And, after the inspection, the adhesive film is striped if necessary from an actuator cut in a given shape and then the actuator is joined to an ink nozzle member via an adhesive. However, it became clear that slight traces of adhesive of the adhesive film remained in the actuator at the time of stripping an adhesive film from the actuator, which resulted in damage to the adhesive effect of an adhesive used between the actuator and the ink nozzle member.